In the prior art, in order to satisfy an office demand of a user, a number of applications capable of offering various office functions have been developed, e.g., email management, a calendar, a memorandum, table making, data making, data management, etc., all of which can perform their particular functions, where many of the applications are managed at respective levels, sub-levels can be created for the applications, and the applications can be extended at several levels so that the respective applications can be accessed more conveniently.
As described above, various formats or various types of data may be generated for the existing numerous office applications. At present the data generated by the large number of office applications cannot be managed centrally.